Decisions Loom for Malaysia Airlines Flight 370 Searchers

Next Phase of Search Would Require Deployment of Submersible Drone

The ADV Ocean Shield continued to search for signals from Flight 370's "black boxes" on Tuesday but failed to find any new leads since the ship's crew last picked up a ping early Sunday.

The likelihood grows with each passing hour that the batteries on the flight's locator beacons have drained. The towed pinger locator, essentially an underwater microphone, will become useless at that point, and will require the search to...